Exploring the relationship between domestic law and international law had been a hobbyhorse of German and French public law scholarship well into the early twentieth century. The relevant debates revolved around two major positions: “dualism”, on the one hand, and “monism”, on the other.
With international co-operation becoming at least moderately successful in the wake of the Second World War, these debates were no longer continued. They came to be regarded as intellectual relics stemming from a different age. Often with little accuracy, they were presented in the introductory chapters of textbooks, based on an understanding that they concern mere constructive matters. They were taken to be irrelevant to the progress of humanity that was to be advanced by international law.
Quite remarkably, the themes relevant to the old debate have been resuscitated in discourses dealing with final authority in the European Union. The themes have become mingled with discussions of federalism and are now presented, without further ado, as issues possessing a constitutional significance. Hence, traditional disputes are recast in a manner that appears to affect, in one way or another, the “constitutionalisation” of the Union.
As is well known, the European constitutionalisation farrago has in the meanwhile spilled over into general international law. Remarkably, the constructive questions revert to their original intellectual habitat, even if in the new cloth of ideas concerning the purported constitution of international law.
As is often the case in intellectual history, when prior debates are almost forgotten the reformulation of older ideas comes dressed up in new vocabulary. What has emerged from the constitutional context of Union Law and begun to reach out into general international law are (relatively) new kids on the block, namely, “pluralism” and “cosmopolitanism”. Adorned with constitutional pathos they are advanced as alternatives to the trite dualist and the long abandoned monist paradigm.
The article argues, first, that pluralism and cosmopolitanism do not really offer any alternatives. Making sense of the relevant positions requires translating them into the conceptual world of the received debate. If defensible, pluralism, either in simple or cosmopolitan form, formulates a new version of monism; if not, it amounts to a travesty of constitutional ideas, which assimilates legality to the mindset of administrative action.
Moreover, it is argued below – in a spirit somewhat reminiscent of Kelsen – that choosing one construction over the other is a question of political philosophy. Monism commends itself not least owing to its superb constitutionalist sensibilities.